The present invention relates to an image sensing apparatus having an image sensing unit and a display unit for reproducing a video output from this image sensing unit.
In the field of cameras, video cameras are recently popular. With a video camera, photographed image information of a dynamic or still image can be recorded on a recording medium, e.g., a magnetic recording medium such as a video tape or a video floppy, or a solid-state memory such as a memory card without performing a development process, unlike a silver halide camera. Additionally, image information which is being photographed or already recorded on a recording medium can be immediately reproduced on a television monitor or the like. Furthermore, along with the recent progress in technology, compact and light weight video cameras become popular, allowing long-time use in outdoors.
Using the above features, video cameras having a compact (3 to 4 inches) liquid crystal display unit combined with a camera, which is used as a view finder in the photographing operation or a reproducing device for reproducing a recorded image, are also widely used because of convenience. On the other hand, apparatuses dedicated to reproduce negative (positive) film image information on a television monitor or convert film image information into an electrical signal and print it by a video printer, or adapters for allowing a photographing operation using a negative (positive) film by a video camera while fixing the film in front of the photographing lens of the video camera are also available.
These apparatuses generally have an illumination unit in addition to a holding unit for holding a photographing lens and an object (film) at a predetermined distance or a mounting unit for mounting the object. By illuminating the film from the back with uniform light obtained by this illumination unit, the photographing operation can be satisfactorily performed. The illumination unit is constituted by a light-emitting unit using a cold cathode-ray tube or the like, an inverter circuit unit for supplying power to the light-emitting unit, a diffusion unit for diffusing light from the light-emitting unit to obtain almost uniform light, and the like.
However, to satisfactorily perform the photographing operation by using such a conventional apparatus, the film must be illuminated, as described above. A special illumination unit is required for this purpose, resulting in an economical disadvantage for the user.
In this case, the following problem is posed due to the influence of a decrease in peripheral light amount of the photographing lens. When an object with a uniform luminance distribution is photographed, the peripheral portion becomes dark as indicated by a solid line in FIG. 3 due to a decrease in peripheral light amount of the photographing lens. Normally, this phenomenon is not so conspicuous. However, in negative-positive reversal, the central portion becomes dark as indicated by a solid line in FIG. 4, resulting in an unnatural image.
Some conventional video recording apparatuses called electronic still cameras or video movie cameras can reproduce photographed video information on a display unit arranged integrally with a camera.
FIG. 24 is a view schematically showing a conventional information recording/reproducing apparatus. Reference numeral 1000 denotes a camera body; 1010, a display unit arranged on the rear surface of the camera body 1000; and 1020, a grip with which the user holds the camera body 1000. The user can observe an object image on the display unit 1010 during or after the photographing operation.
Generally, a liquid crystal display element is used for the display unit 1010. In a liquid crystal display element, however, the allowance of an angle (angle of field) with respect to the line of sight for obtaining a satisfactory image is small. Therefore, to obtain an angle of field for obtaining a satisfactory view of the display unit 1010 while setting the camera body 1000 toward an object in the photographing operation, the user must take a forced posture.
The expensive liquid crystal display element used for the display unit 1010 may be damaged because it is always exposed in use and unused states.
An electronic still camera or a video movie camera as a photographing unit is often used in outdoors. Therefore, when the display unit 1010 is irradiated with a sun beam or the like, it is difficult to satisfactorily view an image reproduced on the display unit 1010.
In the arrangement shown in FIG. 24, the grip 1020 for holding the camera body 1000 is arranged at one end of the camera body 1000. This arrangement causes a moment to act on a hand holding the camera body 1000, resulting in a large load on the user during a long-time photographing operation.
In addition, since a large grasping force is necessary to hold the camera body, it is difficult to operate the release button and the like of the camera with the hand holding the camera body 1000.
The present invention has been made in consideration of the above problems, and has as its object to provide an image sensing apparatus having an image sensing means and a display means for performing a display on the basis of a video output from the image sensing means, which can illuminate an object by using the display means in a photographing operation and reduces an economical load on a user.
It is another object of the present invention to provide an image sensing apparatus capable of photographing an object such as a film without using any dedicated illumination means.
It is still another object of the present invention to provide an image sensing apparatus capable of obtaining an appropriate image while preventing the central portion of the image from becoming dark even in negative-positive reversal without using a special illumination device.
It is still another object of the present invention to provide an image sensing apparatus which can correct a color developed when display means is used as illumination means, thereby easily realizing desired color temperature conversion.
It is still another object of the present invention to provide an image sensing apparatus which can correct a color developed when display means is used as illumination means, thereby removing a desired color component.
It is still another object of the present invention to provide an image sensing apparatus which can detect the luminance distribution of light transmitted through a photographing lens and correct the luminance distribution of illumination light emitted from display means on the basis of the detected luminance distribution, thereby achieving appropriate luminance distribution correction.
It is still another object of the present invention to provide an image sensing apparatus which does not force a user holding the apparatus in an unnatural posture and does not tire the user even in long-time use.
It is still another object of the present invention to provide an image sensing apparatus having an easily operable release button and the like.
It is still another object of the present invention to provide an image sensing apparatus capable of satisfactorily observing display contents on display means.
It is still another object of the present invention to provide an image sensing apparatus which can adjust the positional relationship between photographing means and display means, thereby allowing satisfactory observation of display contents on the display means in a photographing operation.
It is still another object of the present invention to provide an image sensing apparatus which can protect the display surface of display means in an unused state.
It is still another object of the present invention to provide an image sensing apparatus which can easily photograph a sheet-like object such as a film.
It is still another object of the present invention to provide a compact image sensing apparatus.
It is still another object of the present invention to provide an image sensing apparatus which allows a user to satisfactorily observe display contents on display means even when the apparatus is used on a table.
It is still another object of the present invention to provide an image sensing apparatus which can further easily clearly photograph a sheet-like object such as a film.
It is still another object of the present invention to provide an image sensing apparatus which can photograph both an object in front of an image sensing unit and another object behind the image sensing unit.
It is still another object of the present invention to provide an image sensing apparatus which can prevent a power supply from being kept on in an unused state.
In order to achieve at least one of the above objects of the present invention, according to one aspect of the present invention, there is provided an image sensing apparatus which photographs an object by image sensing means having an optical system and an image sensing element and displays a video output on standard display means, in which the display device of the display means can be used to illuminate the object as a photographing target.
For example, using a liquid crystal display device having a light-emitting element (e.g., a backlight consisting of a cold cathode-ray tube) on its rear surface, or a light emission type CRT, a white color can be displayed on the display device which is usable as a surface emission type illumination source.
With this arrangement, when the display color and luminance of the display device are appropriately set, the display means can be used as an illumination lamp without using any additional illumination lamp. Therefore, the cost and weight of the apparatus can be decreased.
According to another aspect of the present invention, holding means for holding display means and image sensing means at a predetermined distance is arranged. The holding means forms a mounting unit for mounting an object on the display surface of the display means. With this arrangement, the mounting unit can be arranged between the image sensing means and the display means so that the display means can be applied as illumination means, and the mounted object can be photographed by the image sensing means. Since an object can be mounted on the display means and photographed by the image sensing means while using the display means as illumination means, a photographing operation can be satisfactorily performed without using any special illumination device.
According to another aspect of the present invention, correction means for correcting the luminance distribution of an object image incident on the image sensing means is provided. With this arrangement, the central portion of an image photographed in negative-positive reversal can be prevented from becoming dark because of a decrease in peripheral light amount of a photographing lens. The luminance distribution correction means enables a satisfactory photographing operation while preventing the central portion of an image photographed in negative-positive reversal.
According to still another aspect of the present invention, image data having luminance distribution characteristics for correcting a decrease in peripheral light amount caused by a photographing lens optical system is stored in a memory. The data is read out in use of display means as illumination means, and displayed on the display means, thereby correcting the luminance distribution. Since image data for correction is stored in the memory, the luminance distribution can be easily corrected.
With the correction means, when the display means is to be used as an illumination source for illuminating an object, illumination light having a luminance distribution for correcting the peripheral light amount of the photographing lens of photographing means can be obtained from the display means. Even when the peripheral light amount of the photographing lens decreases, the photographed image obtains an almost uniform light amount because correction can be performed on the illumination light emission side. Therefore, no expensive photographing lens whose peripheral light amount is improved need be used. In addition, a limitation on design is reduced, so that the product cost can be reduced.
According to another aspect of the present invention, correction means causes the display device of display means to emit light at a uniform luminance level. This light is photographed by image sensing means, and correction is performed on the basis of the photographing result such that an image output from the image sensing means is at a uniform level.
According to this arrangement, there is provided a method of correcting a luminance distribution. First, a display surface is caused to uniformly emit light to check a decrease in peripheral light amount of the photographing lens at that time. Subsequently, to correct the decrease in peripheral light amount of the lens, the luminance is corrected such that the light amount of the display light increases outward, thereby eliminating the influence of a decrease in peripheral light amount of the photographing lens.
According to still another aspect of the present invention, the display means has color correction means for arbitrarily setting the color of light emission on the di splay device.
With this arrangement, color temperature conversion of a negative or positive film can be performed. The same effect as in a photographing operation using a color filter mounted on an object can be obtained, so that a work according to the taste of the user can be obtained.
According to still another aspect of the present invention, the color correction means has a function of executing illumination using the display means in accordance with a desired color development level on a photographed image to convert the color temperature of the photographed image.
With this arrangement, for example, when the color temperature of the photographed image is to be lowered, the intensity of the R signal of a display image used for illumination must be increased. With this processing, the color temperature of a photographed image can be arbitrarily converted.
According to another aspect of the present invention, when a color component in the object is to be removed from the photographed image, the color correct ion means performs illumination in a similar color by using the display means.
With this arrangement, for example, when a green line is to be erased from the photographed image of an object, a display color having green spectral characteristics is displayed on the display means, with which the object is illuminated. With this operation, a specific color on an object can be erased from a photographed image, thereby removing an arbitrary color component from the photographed image.
According to still another aspect of the present invention, the image sensing means and the display means are coupled with each other while the distance therebetween is adjustable. For example, when the image sensing means and the display means are integrated with each other through a parallel link mechanism, the interval, i.e., the distance between an object and the image sensing means and the relative position can be freely changed.
According to still another aspect of the present invention, there is also provided an image sensing apparatus comprising a first housing accommodating image sensing means having a photographing optical system and an image sensing element for converting an optical image formed by the photographing optical system into an electrical signal, and a second housing accommodating display means for displaying an image on the basis of a video output from the image sensing means, wherein the first and second housings are fixed to free to pivot about a rotating shaft. With this arrangement, the image sensing apparatus can be folded and made compact. When video information is to be reproduced in outdoors, the image sensing unit serves as a visor for preventing a sun beam from being directly incident on the display means, so that a satisfactory view of the display means can be obtained.
According to still another aspect of the present invention, the first housing can be folded to shield the display surface of the display means. With this arrangement, the display means can be protected by folding the image sensing unit.
According to still another aspect of the present invention, the image sensing means has holding means for holding or positioning a sheet-like object such as a film in front of the photographing optical system. With this arrangement, a sheet-like object such as a film can be easily photographed.
According to still another aspect of the present invention, the second housing has mounting means for detachably mounting an almost flat card-like recording unit for recording a video signal obtained by the image sensing means and an almost flat card-like power supply unit for supplying power to the entire apparatus. The recording unit and the power supply unit are mounted such that the respective flat surfaces are stacked almost parallel to the display surface of the display means in the vertical direction. With this arrangement, the apparatus, and particularly the second housing can be made compact.
According to still another aspect of the present invention, the image sensing apparatus has angle holding means capable of holding the display surface at an arbitrary angle with respect to the horizontal plane. With this arrangement, the angle of the display means with respect to the user can be adjusted when the apparatus is placed on a table.
According to still another aspect of the present invention, the photographing optical system of the image sensing means is constituted by a zoom optical system capable of changing the photographing magnification and has a holding unit for holding or positioning a sheet-like object such as a film in front of the zoom optical system, and a detection unit for detecting that the sheet-like object is held or positioned by the holding unit. When the detection unit detects that the sheet-like object is held or positioned, the photographing optical system is set at a predetermined zoom magnification. With this arrangement, a sheet-like object such as a film can be further easily clearly photographed.
According to still another aspect of the present invention, the image sensing means has a pivotal incident light reflection means, a first photographing window for photographing a sheet-like object, and a second photographing window for photographing another object on the opposite side. With this arrangement, both the object in front of the image sensing unit and the object behind the image sensing unit can be photographed.
According to still another aspect of the present invention, the ON/OFF state of the power supply is controlled on the basis of an angle formed between the first housing and the second housing. For example, when the image sensing unit (first housing) is folded on the display unit (second housing) side, the power supply is automatically turned off. With this arrangement, the power supply can be prevented from being kept in an unused state.
According to still another aspect of the present invention, the apparatus can be held such that a surface of the housing accommodating the display means capable of displaying at least video information, which is on an opposite side of a surface where the display means is present, is in contact with a hand of the user holding the housing. With this arrangement, the apparatus can be easily held without being firmly gripped.
According to still another aspect of the present invention, operation switches are arranged to be operable with a finger of a hand holding the housing accommodating the display means. The operation switches include a release button for designating the start of recording video or speech information by the image sensing means or the start of reproduction of video information by the display means. Therefore, the release button is arranged to be operable with a finger of the left or right hand of the user who is holding the housing accommodating the display means, so that the release button can be easily operated.
According to still another aspect of the present invention, the housing accommodating the display means has a surface inclined with respect to the display surface, and the operation switches are arranged on this inclined surface.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.